Make streusel topping (see recipe below) and stick in the fridge for 30 minutes to chill while you make your muffin mix.
Add butter and eggs into a large bowl or mixer and beat on high until light and fluffy. Add eggs one at a time beating after each addition. Add vanilla.
Gradually add in flour, baking soda, baking powder, and salt. Add sour cream and stir until just combined.
Preheat your oven to 350 and put paper liners in two muffin tins. Divide your batter evenly among your cups (I use a 1/4 cup measuring cup to scoop). Sprinkle half of your streusel topping evenly over muffins and gently press down into your batter with your hand, then sprinkle the remaining batter evenly over each muffin.
Bake muffins until a toothpick comes out clean, usually 18-20 minutes, rotating tins halfway through bake time.
Mix your glaze and use a spoon to drizzle over your muffins. Enjoy!
These coffee cake muffins are amazing! They freeze great and save in the fridge for 7-10 days!